As an electric power steering apparatus in the past, for example, there has been proposed an electric power steering apparatus in which a motor is housed in a part of a rack case or a steering gear box in which a rack shaft is slidably housed or mounted, a housing in which a control board for controlling to drive the motor is housed is formed in the rack case or the steering gear box, and, when the control board inserted from an opening of the housing is brought into contact with an attachment boss formed in a bottom portion opposed to the opening, a board connection terminal provided in the control board comes into contact with a motor side connection terminal protrusionly provided in the housing and electrically connected thereto (see, for example, JP2005-329866A (hereinafter referred to as Patent Document 1), JP2005-329867A (hereinafter referred to as Patent Document 2), JP2005-329868A (hereinafter referred to as Patent Document 3), and JP2005-329869A (hereinafter referred to as Patent Document 4)).
On the control board, a CPU is attached on a front surface side, a capacitor, a power relay, and the like are disposed and a supporting board serving as a heat sink is protrusionly provided on a rear surface side, and an FET (field effect transistor) is attached to this supporting board.
Connectors for power supply and input and output of signals from the outside are projected and formed near the steering gear box and on an upper surface cover of the housing in parallel to an input shaft of the steering gear box to prevent a flying stone or the like from hitting the connectors and is configured such that connector connection is performed from above.
On the other hand, as a column-type electric power steering apparatus in the past, for example, there has been proposed an electric power steering apparatus having the structure in which an input shaft and an output shaft are connected via torsion bar, a worm gear mechanism that transmits torque of an electric motor to the output shaft, a magnetic sensor that is arranged in a steering column side position of this worm gear mechanism and detects steering torque, and a switching transistor set on an outer peripheral side of this magnetic sensor are mounted in a housing, and a control board is disposed on a cover that closes a magnetic sensor side opening end of the housing (see, for example, JP2004-106703A (hereinafter referred to as Patent Document 5)).